Los fuegos artificiales brillan e iluminan la feria.

This is just the standard Spanish expression for fireworks.

• fuego = fire
• artificial = artificial
• fuegos artificiales = fireworks

Spanish often uses expressions that do not translate word-for-word naturally into English. So even though the literal idea is artificial fires, the real meaning is simply fireworks.

Also note that this expression is normally used in the plural when talking about fireworks in general.

Spanish often uses the definite article more than English does.

So Los fuegos artificiales means:

• The fireworks
• or sometimes just Fireworks, depending on context

In English, we often omit the in general statements, but Spanish commonly keeps it. Here, los agrees with the plural noun fuegos.

Because it must agree with fuegos, which is masculine plural.

Agreement in Spanish means adjectives change form to match the noun:

• fuego artificial = an artificial fire
• fuegos artificiales = fireworks

Here:

• fuegos = plural
• so artificiales must also be plural

Because the subject is Los fuegos artificiales, which is third person plural.

So the verbs must match that subject:

• brillan = they shine
• iluminan = they light up / illuminate

This is standard subject-verb agreement.

The infinitives are:

• brillar = to shine
• iluminar = to illuminate / to light up

In the sentence, both are in the present tense, third person plural:

• brillan = they shine
• iluminan = they illuminate

This is a very common Spanish spelling-and-sound rule.

Normally, and is y. But it changes to e before a word that begins with an i sound, to avoid an awkward repetition of sounds.

So:

• brillan y cantan = they shine and sing
• brillan e iluminan = they shine and illuminate

Because iluminan starts with an i sound, Spanish uses e instead of y.

Usually yes, before an i sound, but not in every possible case.

Examples:

• padre e hijo = father and son
• España e Italia = Spain and Italy

But if the word begins with hi and the i sound is not really pronounced immediately in the same way, Spanish may still keep y in some cases. For beginner purposes, the main rule to remember is:

• Use e instead of y before words beginning with i or hi sounding like i.

La feria can mean different things depending on context, such as:

• fair
• festival
• funfair
• local celebration

In Spain, feria often refers to a festive public event, sometimes with rides, lights, food, music, and celebrations. So here it likely means the fairgrounds or the fair/festival area.

Because it refers to one fair or one festival/event.

• la feria = the fair
• las ferias = the fairs

In this sentence, the fireworks are shining and lighting up the fair, so singular is the natural choice.

Yes, Spanish often allows the subject to be omitted because the verb ending already shows who is doing the action.

So both are possible:

• Los fuegos artificiales brillan e iluminan la feria.
• Brillan e iluminan la feria.

The full version is clearer and more explicit. The version without the subject would depend more on context.

Because one subject can have multiple actions.

Here, Los fuegos artificiales does two things:

• brillan = shine
• e iluminan la feria = and light up the fair

This works just like English:

• The fireworks shine and light up the fair.

You do not need to repeat the subject before the second verb.

Not exactly.

• iluminar = to illuminate, to light up
• encender = to switch on, light, ignite

So in this sentence, iluminan la feria means the fireworks make the fair bright or visible. It does not mean they are turning it on like a switch.

A simple approximate pronunciation is:

• bree-yan or bree-llan, depending on accent

In much of Spain, ll is commonly pronounced like the y in yes.

So:

• brillan sounds roughly like BREE-yan

The rr sound is not used here; it is a single r in brillar, so it is softer than the strong rolled rr in words like perro.

Roughly:

• FEH-ree-ah

In Spain Spanish:

• fe as in a short feh
• ri like ree
• a as a clear final ah

So feria has three syllables: fe-ri-a.

Because Spanish often uses the same basic order:

• Subject + verb + object

Here:

• Los fuegos artificiales = subject
• brillan e iluminan = verbs
• la feria = object of iluminan

Spanish can be more flexible with word order than English, but this sentence uses a very straightforward, neutral structure.

Yes. brillar can be literal or figurative.

Literal:

• Las estrellas brillan. = The stars shine.

Figurative:

• Ella brilla en el escenario. = She shines on stage.

In your sentence, it is clearly literal: the fireworks are physically shining.

Yes, it sounds natural and correct.

It is a simple descriptive sentence with:

• a clear subject
• two present-tense verbs
• correct use of e before iluminan

A native speaker might also say similar versions such as:

• Los fuegos artificiales brillan y llenan de luz la feria.
• Los fuegos artificiales iluminan la feria.

But your sentence is perfectly normal Spanish.